Method for manufacturing inner structure of regenerative cooling type combustion chamber

ABSTRACT

The present invention relates to a method for manufacturing an inner structure of a regenerative cooling type combustion chamber, and more specifically to a method for manufacturing the inner structure of the regenerative cooling type combustion chamber, including the steps of: manufacturing a cylinder structure by performing a vacuum casting process or an air casting process for a copper alloy; manufacturing a circular plate having a constant thickness by forging and rolling the cylinder structure; thermally and mechanically processing the circular plate; spinning the circular plate to manufacture the shape of the regenerative cooling type combustion chamber; and thermally processing the shape of the regenerative cooling type combustion chamber. The method for manufacturing the inner structure of the regenerative cooling type combustion chamber can prevent necking and damage of the structure and can improve reliability during a bulging process for assembling the inner structure with an outer structure of the combustion chamber by uniformizing and miniaturizing the grain size of the inner structure of the combustion chamber.

TECHNICAL FIELD

The present invention relates to a method of manufacturing an inner liner of a regenerative cooling combustion chamber, and more particularly to a method of manufacturing an inner liner of a regenerative cooling combustion chamber, which includes the steps of manufacturing a cylinder structure with copper alloy through a vacuum or atmosphere casting process; manufacturing a circular plate having a certain thickness by forging and rolling the cylinder structure; and performing thermal treatment after thermally treating, machine work and spinning the circular plate to have a shape of a regenerative cooling combustion chamber, so that the inner liner of the combustion chamber can have uniform and fine grains and thus the inner liner to be coupled to the outer jacket of the combustion chamber can be prevented from necking or damage during a bulging process, thereby having an effect on improving reliability.

BACKGROUND ART

In general, an inner liner and an outer jacket made of different materials are assembled into a regenerative cooling combustion chamber for a liquid rocket combustor. The inner liner is made of copper alloy showing high thermal conductivity and strength to protect a chamber structure from high temperature combustion gas generated in the combustion chamber, and worked to have a cooling channel through which fuel can flow for cooling. The outer jacket is generally made of high strength steel showing very high strength coupled to an outside of the inner liner so that the chamber can structurally stably operate against the high pressure combustion gas generated inside the combustion chamber,

As a method of manufacturing the foregoing combustion chamber, there are two major methods currently used all over the world.

In a first method, the inner liner made of copper alloy is worked to have a chamber shape with the cooling channel, and nickel (Ni) layer is formed at the outside of the inner liner by electroforming, thereby completing the regenerative cooling combustion chamber. As a combustor manufactured by this method, there is a VULCAIN thrust combustor.

In a second method, currently used in Russia and Korea, the copper alloy inner liner and the outer jacket are worked. and then assembled to undergo brazing. At this time, the copper alloy inner liner and the high strength steel outer jacket are worked to have desired shapes and then assembled for brazing.

FIG. 1 is a schematic view showing the shape of the regenerative cooling combustion chamber, and FIG. 2 is a schematic view of a bulging process.

As shown in FIG. 1, the present shape has difficulty in assembling the inner liner and the outer jacket since a cylinder section 20 and a nozzle section 30 have larger diameters than a nozzle neck 10. Therefore, the copper alloy inner liner and the outer jacket are designed/manufactured for easily assembling. After both jackets are assembled, the bulging process is performed to transform the inner liner from a cylinder shape to a nozzle shape as shown in FIG. 2, thereby manufacturing the regenerative cooling combustion chamber.

When the cylinder section of the copper alloy inner liner is transformed into the nozzle shape by the bulging process, large deformation occurs in the cylinder section. In general, necking or damage may occur in a metallic material if it is transformed beyond its forming limit. Also, even though the same metallic material is used, the metallic material having large and non-uniform grains is more likely to cause necking or damage than that having small and uniform grains. In manufacturing regenerative cooling combustion chamber for a liquid rocket, if the cylinder section of the copper alloy inner liner is transformed to have a nozzle shape, the large deformation occurs to thereby cause the necking or damage during the bulging process. Therefore, to prevent the inner liner from being damaged by the deformation occurring in the bulging process, a degree of deformation occurring in the jacket has to be decreased by shortening the length of the cylinder section to be bulged, i.e., by reducing an enlarging ratio of the finally transformed nozzle. In this case, an end of the nozzle transformed by the bulging process is connected to a nozzle extending portion due to a larger enlarging ratio. A region in the combustion chamber, where the largest thermal load due to combustion gas is applied, is a nozzle throat portion. When EBW (Electron Beam Welding) location of bulged nozzle end with the larger nozzle section is performed at a portion closer to the nozzle throat, the thermal load are gradually increased. Therefore, EBW location should be far away from the nozzle throat as possible because cooling performance of EBW location is low. That's why the nozzle formed by the bulging process is designed to have the maximum enlarging ratio by taking a forming limit of a material into account. It is very important that the cylinder shape of inner liner is transformed into the nozzle shape by the maximum diameter enlarging ratio without the necking or damage. The copper alloy inner liner undergoes the bulging process in the state that the cooling channel is worked. To precisely work the cooling channel, much time and costs are needed. Thus, if the bulging process is failed, a serious loss occurs in the time and costs. Accordingly, material characteristics are very important to prevent the necking and damage while the copper alloy inner liner is transformed to have a designed nozzle shape.

To manufacture such an inner liner of the regenerative cooling combustion chamber, as shown in FIGS. 3 and 4, copper alloy is conventionally casted to have a circular bar shape, and then forged to work the inner liner. Specifically, it is general that the copper alloy 1 is forged through hammering and then worked to have the shape of the inner liner 2 (refer to FIG. 3), or that the copper alloy 1 is pierced with a forging rod, forged through hammering, and worked to have the shape of the inner liner 2 (refer to FIG. 4).

However, after the inner liner is formed by the conventional methods shown in FIGS. 3 and 4, a result from analyzing the material microstructure of the inner liner shows that the grains are very large and non-uniformly distributed. If the grains are large and non-uniformly distributed, small deformation may cause the necking or damage in the jacket when the nozzle shape is manufactured by the bulging method. The reason why the necking or damage occurs is because the shape of the chamber to be manufactured is circular. The circular shape of the jacket to be worked to have such a shape is difficult to uniformly give a forging effect to the material.

Accordingly, there is needed a new manufacturing method for preventing the necking and damaging problems due to the non-uniform forging effect in the bulging process.

DISCLOSURE Technical Problem

The present invention is conceived to satisfy the foregoing requirements, and an aspect of the present invention is to provide a method of manufacturing an inner liner of a regenerative cooling combustion chamber, and more particularly to a method of manufacturing an inner liner of a regenerative cooling combustion chamber, which includes the steps of manufacturing a cylinder structure with copper alloy through a vacuum or atmosphere casting process; manufacturing a circular plate having a certain thickness by forging and rolling the cylinder structure; and performing thermal treatment after thermally treating, working and spinning the circular plate to have a shape of a regenerative cooling combustion chamber, so that the inner liner of the combustion chamber can have uniform and fine grains and thus the inner liner to be assembled to the outer jacket of the combustion chamber can be prevented from necking or damage during a bulging process, thereby having an effect on improving reliability.

Technical Solution

In accordance with one aspect of the present invention, there is provided a method of manufacturing an inner liner of a regenerative cooling combustion chamber, the method including: manufacturing a cylinder structure with copper alloy through a vacuum or atmosphere casting process; manufacturing a circular plate having a certain thickness by forging and rolling the cylinder structure; and thermally treating, working and spinning the circular plate to have a shape of a regenerative cooling combustion chamber.

The method may further include performing thermal treatment to recrystallize the jacket manufactured to have the shape of the regenerative cooling combustion chamber after finishing the spinning work.

The copper alloy may include copper, chrome, iron, lead, zinc, magnesium, nickel, and silicon. In more detail, the copper alloy may include chrome of 0.4˜0.7 wt %, iron of 0.06 wt % or below, lead of 0.005 wt %, zinc of 0.015 wt % or below, magnesium of 0.002 wt % or below, nickel of 0.02 wt % or below, silicon of 0.05 wt % or below, phosphorus of 0.01 wt % or below, and a remnant of copper in the total weight of copper alloy.

Advantageous Effects

In accordance with an aspect of the present invention, there is provided a method of manufacturing the inner liner of the regenerative cooling combustion chamber, in which copper alloy has uniform and fine grains so that the jacket can be prevented from necking or damage during a bulging process necessarily performed when the combustion chamber is manufactured by a brazing method, thereby decreasing a loss of time and coasts due to failed bulging in manufacturing the regenerative cooling combustion chamber, and increasing fatigue life of the regenerative cooling combustion chamber under repetitive thermal, pressure load by combustion tests.

DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view showing the shape of the regenerative cooling combustion chamber.

FIG. 2 is a schematic view of a bulging process.

FIG. 3 is a schematic view of a conventional forging process where a casted circular bar is worked into an inner liner.

FIG. 4 is a schematic view of a conventional forging process where a center of a casted circular bar is formed with a hole and then a forging rod is inserted therein to be worked into an inner liner.

FIG. 5 is a flowchart of a manufacturing method of a regenerative cooling combustion chamber according to an embodiment of the present invention.

FIG. 6 is a schematic view showing that copper alloy materials are fused, forged, rolled and machine-worked before spinning work, as a part of the manufacturing method of a regenerative cooling combustion chamber according to an embodiment of the present invention.

FIG. 7 is a schematic view showing that spinning work is applied to the cooper alloy product manufactured in FIG. 6 to have a shape of a combustion chamber, as a part of the manufacturing method of a regenerative cooling combustion chamber according to an embodiment of the present invention.

BEST MODE

Hereinafter, exemplary embodiments according to the present invention will be described to be easily embodied by a person having an ordinary skill in the art to which the present invention pertains.

Prior to this, terms or words used in this specification and claims have to be interpreted as the meaning and concept adaptive to the technical idea of the present invention rather than typical or dictionary interpretation on a principle that an inventor is allowed to properly define the concept of the terms in order to explain his/her own invention in the best way.

Therefore, embodiments disclosed in this specification and configurations illustrated in the drawings are nothing but preferred examples of the present invention and do not fully describe the technical idea of the present invention, and it will be thus appreciated that there are various equivalents and alterations replacing them at a filing date of the present application.

Hereinafter, an embodiment of the present invention will be described in detail with reference to accompanying drawings.

FIG. 5 is a flowchart of a manufacturing method of a regenerative cooling combustion chamber according to an embodiment of the present invention.

As shown in FIG. 5, a method of manufacturing an inner liner of a regenerative cooling combustion chamber according to the present invention includes manufacturing a cylinder structure with copper alloy through a vacuum or atmosphere casting process; manufacturing a circular plate having a certain thickness by forging and rolling the cylinder structure; and thermally treating, working and spinning the circular plate to have a shape of a regenerative cooling combustion chamber.

FIG. 6 is a schematic view showing that copper alloy materials are fused, forged, rolled and machine-worked before spinning work, as a part of the manufacturing method of a regenerative cooling combustion chamber according to an embodiment of the present invention, and FIG. 7 is a schematic view showing that spinning work is applied to the cooper alloy product manufactured in FIG. 6 to have a shape of a combustion chamber, as a part of the manufacturing method of a regenerative cooling combustion chamber according to an embodiment of the present invention. With reference to FIGS. 6 and 7, the method of manufacturing the inner liner of the regenerative cooling combustion chamber according to an embodiment of the present invention will be described.

First, as shown in FIG. 6, copper, chrome, iron, lead, zinc, magnesium, nickel, silicon and other metals are put into a smelting furnace and made into casting 100 for manufacturing copper alloy. Here, other metals used in manufacturing the copper alloy may include chrome of 0.4˜0.7 wt %, iron of 0.06 wt % or below, lead of 0.005 wt %, zinc of 0.015 wt % or below, magnesium of 0.002 wt % or below, nickel of 0.02 wt % or below, silicon of 0.05 wt % or below, phosphorus of 0.01 wt % or below in the total weight of copper alloy.

The copper alloy casting 100 manufactured as above undergoes a forging process where it is forged with pressure and shock under plastic flow state, and cast structures thus become a uniform organization. Therefore, the copper alloy forging 200 is manufactured. Here, the forging process is obvious to those skilled in the art, and therefore detailed descriptions thereof will be omitted.

After the forging process is completed, the copper alloy forging 200 is rolled while passing through a rolling mill and being heated at a temperature higher or lower than a recrystallization temperature. Through the rolling process, a cast structure is uniformly deformed and thickness is decreased. Thus, the rolled copper alloy 300 is manufactured. Here, the rolling process is obvious to those skilled in the art.

After the rolling process is completed, the rolled copper alloy 300 is thermally treated to make the grains fine, and the inner liner manufactured to be shaped like a chamber through the following spinning process is machine-worked to have an opening portion 410, thereby manufacturing the copper alloy product 400.

When the thermal treatment and the machine work are completed, the spinning process is performed. As shown in FIG. 7, the copper alloy product 400 is first mounted to spinning equipment X having a straight incline and then pushed with a roller Y, thereby performing spinning work (refer to 7 a). Here, the opening portion 410 of the copper alloy product 400 is put in and fixed to one end of the spinning equipment X in an axial direction, thereby facilitating the work.

After the shear spinning work is completed, the copper alloy product 400 is mounted to spinning equipment X′ having a curved slope shaped like the combustion chamber as shown in FIG. 7 b, and then undergoes spinning work.

In this case, the copper alloy product 400 is worked to have the shape of the combustion chamber as shown in FIG. 7, and thermally treated to have uniform and fine grains. At this time, both hot and cold processes are possible for the spinning process. However, the cold process is preferable to make the grains fine and uniform through the following heat treatment. A processing temperature at the hot process may be equal to or lower than the recrystallization temperature of the material. If the processing temperature is beyond the above temperature range, the grains of the jacket become coarse after the final process

An embodiment of the present invention may further include performing the thermal treatment for recrystallizing the inner liner manufactured to have the shape of the regenerative cooling combustion chamber after finishing the spinning work. Through this thermal treatment, the grains of the copper alloy can get finer and more uniform. The thermal treatment may be performed at a temperature of 600˜900° C. If the thermal treatment is performed beyond this temperature range, the recrystallization is not performed or the grains become coarse

Although some embodiments have been described herein with reference to the accompanying drawings, it will be understood by those skilled in the art that these embodiments are provided for illustration only, and various modifications, changes, alterations and equivalent embodiments can be made without departing from the scope of the present invention. 

1. A method of manufacturing an inner liner of a regenerative cooling combustion chamber, the method comprising: manufacturing a cylinder structure with copper alloy through a vacuum or atmosphere casting process; manufacturing a circular plate having a certain thickness by forging and rolling the cylinder structure; and thermally treating, working and spinning the circular plate to have a shape of a regenerative cooling combustion chamber.
 2. The method according to claim 1, further comprising performing thermal treatment to recrystallize the jacket manufactured to have the shape of the regenerative cooling combustion chamber after finishing the spinning work.
 3. The method according to claim 1, wherein the copper alloy comprises copper, chrome, iron, lead, zinc, magnesium, nickel, and silicon.
 4. The method according to claim 1, wherein the copper alloy comprises chrome of 0.4˜0.7 wt %, iron of 0.06 wt % or below, lead of 0.005 wt %, zinc of 0.015 wt % or below, magnesium of 0.002 wt % or below, nickel of 0.02 wt % or below, silicon of 0.05 wt % or below, phosphorus of 0.01 wt % or below, and a remnant of copper in the total weight of copper alloy. 